A fuel terminal is an industrial facility that stores oil or petrochemical products and from which these products are transported to end users or further storage facilities. A fuel terminal typically has storage tankage, either above ground or underground, and gantries that support the transfer of products from the tankage into fuel tanker trailers or other vehicles. A loading rack is a mechanism for delivering fuel from fuel terminal tankage into a fuel tanker trailer or other means of transfer outside of the fuel terminal.
Fuel tanker trailers carry fuel in multiple compartments that are generally filled from the bottom. For safety reasons, fluid overfill sensors are placed in each compartment of the trailer to detect potential fluid overfills and provide a signal indicative of an overfill fluid level in a given compartment. Additionally, the trailer is electrically grounded during the filling process to safely dissipate hazardous static electrical charges that could ignite flammable fluids and vapors. During the filling process, the signals provided by the fluid overfill sensors are monitored by a fluid monitoring controller to identify imminent fluid overfills and to prevent their occurrence by causing the loading rack to stop the filling process. The fluid monitoring controller may be an on-board controller integrated with the fuel tanker trailer or a controller integrated with the loading rack. Also, the ground signal is monitored to ensure that the trailer is properly grounded. The fluid monitoring controller should be tested periodically to verify proper operation.